Process and apparatus for producing fiber-reinforced thermoplastic resin tape

ABSTRACT

Provided are a process and an apparatus for producing a fiber-reinforced thermoplastic resin tape, the process and the apparatus being capable of preventing fiber cut from occurring at the start of production of the fiber-reinforced thermoplastic resin tape. The provided process includes a resin impregnation step of opening a fiber bundle and impregnating the fiber bundle with molten thermoplastic resin and a through-nozzle passing step of passing the fiber bundle having undergone the resin impregnation step through a slit formed in a nozzle. The through-nozzle passing step includes setting, at the start of production, a gap dimension of the slit to a dimension larger than a normal dimension and changing the gap dimension of the slit to the normal dimension when a predetermined condition is satisfied, after the production start.

TECHNICAL FIELD

The present invention relates to a process and an apparatus forproducing a tape made of fiber-reinforced thermoplastic resin formed byimpregnating fibers with thermoplastic resin.

BACKGROUND ART

As a technique concerning production of a carbon fiber-reinforcedthermoplastic resin tape, there has been known, for example, a techniquedescribed in Patent Literature 1. This method uses a nozzle. The nozzleincludes a nozzle upper member and a nozzle lower member, the twomembers defining therebetween a slit with a given gap equal to orsmaller than 130 pm. The nozzle further includes urging means for urgingthe nozzle upper member and the nozzle lower member in the direction ofreducing the interval. The method includes a step of passing a carbonfiber strand impregnated with thermoplastic resin through the slit ofthe nozzle to thereby draw out a thermoplastic-resin-impregnated tapehaving a tape thickness equal to or smaller than 130 μm from the nozzle.

Paragraph 0026 of the specification of Patent Literature 1 mentions:that accumulation of feather in a downstream-side slit nozzle can raisethe surface pressure of a molten resin contact surface; the rise of thesurface pressure involves decrease in the pressing force of a pressurecylinder corresponding to the urging means to allow ascent of the nozzleupper member and/or descent of the nozzle lower member, thereby allowingthe feather to be drawn out from the downstream-side slit nozzletogether with the tape to eliminate the accumulation of the feather; andthe suppression of the accumulation of the feather makes it possible tohinder the fibers from being cut.

However, the technique described in Patent Literature 1, that is, thetechnique for urging the nozzle upper member and the nozzle lower memberdefining the slit in the directions of reducing the intervaltherebetween is presented for preventing fibers from being cut duringproduction of the resin-reinforced thermoplastic resin tape, taking noaccount of circumstances at the start of production. The inventors havefound a tendency of fiber cut particularly at the start of production ofthe fiber-reinforced thermoplastic resin tape. Continuing operationwhile leaving such fiber cut generates possibility that the fiber havingcut clogs the nozzle to cause all of the fibers constituting the tape tobe cut. This problem occurs in high frequency particularly in the caseof producing a fiber-reinforced thermoplastic resin tape having highcontent of fibers and small tape thickness.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No.2007-118216

SUMMARY OF INVENTION

An object of the present invention is to provide a process and anapparatus for producing a fiber-reinforced thermoplastic resin tape, theprocess and the apparatus being capable of suppressing occurrence offiber cut at the start of production of the fiber-reinforcedthermoplastic resin tape.

Provided is a process for producing a fiber-reinforced thermoplasticresin tape, the process including: a resin impregnation step of openinga fiber bundle and impregnating the opened fiber bundle with moltenthermoplastic resin; and a through-nozzle passing step of passing thefiber bundle having undergone the resin impregnation step through a slitformed in a nozzle to form the resin bundle into a tape shape. Thethrough-nozzle passing step includes passing the fiber bundle, at thestart of production, through the slit in a state where the slit has agap dimension larger than a normal dimension corresponding to a targetthickness dimension of the fiber-reinforced thermoplastic resin tape andchanging the gap dimension of the slit, at a point in time when apredetermined condition is satisfied after the start of production, intothe normal dimension and then passing the fiber bundle through the slit.

Also provided is an apparatus for producing a fiber-reinforcedthermoplastic resin tape, the apparatus including: a resin impregnationdevice that opens a fiber bundle and impregnates the opened fiber bundlewith molten thermoplastic resin; and a nozzle provided in an outletsection of a container of the resin impregnation device and defining aslit allowing the fiber bundle impregnated with the thermoplastic resinto pass through the slit, the nozzle bringing the fiber bundle passingthrough the slit into a tape shape. The nozzle includes a dimensionselection mechanism allowing a gap dimension of the slit defined by thenozzle to be selected between a normal dimension equivalent to a targetthickness dimension of the fiber-reinforced thermoplastic resin tape anda production-start dimension larger than the normal dimension.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a production apparatus for afiber-reinforced thermoplastic resin tape according to an embodiment ofthe present invention.

FIG. 2 is an enlarged view of a supply machine included in theproduction apparatus.

FIG. 3A is an enlarged view of a nozzle included in the productionapparatus.

FIG. 3B is a view of the nozzle included in the production apparatusviewed from a direction of an arrow Al in FIG. 1.

FIG. 4 is a view of a state of the nozzle at the start of productionviewed from the direction of the arrow Al.

FIG. 5 is a view of a grooved roller included in the productionapparatus viewed from the direction of the arrow Al.

FIG. 6 is a plan view of the production apparatus.

FIG. 7A is a partial sectional side view showing a nozzle according to amodification and is a view equivalent to FIG. 3A.

FIG. 7B is a front view showing the nozzle according to themodification, the view corresponding to FIG. 3B.

DESCRIPTION OF EMBODIMENTS

There is explained below an embodiment for carrying out the presentinvention, with reference to the drawings. Specifically, explained isthe configuration of a production apparatus for a fiber-reinforcedthermoplastic resin tape, while a production process for thefiber-reinforced thermoplastic resin tape is explained.

(As to a Production Apparatus for a Fiber-Reinforced Thermoplastic ResinTape)

FIG. 1 shows a production apparatus 100 for a fiber-reinforcedthermoplastic resin tape according to the embodiment. The productionapparatus 100 performs production of a fiber-reinforced thermoplasticresin tape with conveyance of a fiber bundle 8, including a supplymachine 1, a preheating machine 2, a resin impregnation device 3, anozzle 18, a roller cooling section 4, a cooling section 5, a pullingmachine 6, and a winding-up machine 7 arranged in this order from theupstream side of the conveyance direction of the fiber bundle 8.

<Feeding Machine>

The supply machine 1 includes a bobbin 11, a guide bar 12, a dancerroller 13, a guide roller 14, and a tension adjusting mechanism 31 shownin FIG. 2.

On the bobbin 11 is wound a fiber bundle 8 formed of, for example,approximately 12,000, bundled fibers. Each of the fibers constitutingthe fiber bundle 8 according to this embodiment is a carbon fiber, butthe present invention is not limited to this. As the fiber constitutinga fiber bundle according to the present invention, there can be used,for example, a glass fiber, an aramid fiber, a ceramics fiber, a metalfiber, and a continuous fiber such as fiber obtained from heterocyclicring containing polymer formed of polybenzochiazole, polybenzoxazole, orthe like. Also natural vegetable fiber produced by spinningdiscontinuous fibers into a thread can be used. As the carbon fiber canbe used, for example, polyacrylonitrile (PAN) based, petroleum/coalpitch based, rayon based, or lignin based carbon fibers.

The guide bar 12, while having a circular cross section, is disposed soas to be prevented from rotating around the center axis of the guide bar12. In contrast, the dancer roller 13 and the guide roller 14, havingcircular cross sections, are disposed to be allowed to rotate aroundrespective center axes thereof. Furthermore, the dancer roller 13 isdisposed movably up and down so as to allow the rotation center axis ofthe dancer roller 13 to move vertically.

The fiber bundle 8 is supplied from the bobbin 11 and conveyed whilecoming into contact with each of the guide bar 12, the dancer roller 13,and the guide roller 14, while constant tension is applied to the fiberbundle 8. The tension is adjusted by the dancer roller 13 and thetension adjusting mechanism 31. The force for conveyance (traveling) ofthe fiber bundle 8 is applied by the pulling machine 6 pulling the fiberbundle 8. The fiber bundle 8 is, thus, pulled up to the pulling machine6 with the constant tension applied to the fiber bundle 8.

The tension adjusting mechanism 31 operates to keep the tension actingon the fiber bundle 8 constant. The tension adjusting mechanism 31includes, as shown in FIG. 2, a bar member 32 connected to the centershaft of the dancer roller 13, a tension applying weight 33 provided onthe bar member 32, an angle detector 34 attached to the bar member 32, amotor 35 that rotates the bobbin 11, and a controller 36.

The bar member 32 includes a distal end portion connected to the dancerroller 13 and a proximal end portion opposite to the distal end portion,being disposed so as to be able to make rotational movement around theproximal end portion to allow the dancer roller 13 to move up and down.The tension applying weight 33 applies a downward urging force havingconstant magnitude to the dancer roller 13 through the gravity acting onthe tension applying weight 33. The angle detector 34 detects an angleof the rotational movement of the bar member 32 around the proximal endportion.

The controller 36 is electrically connected to the motor 35 and theangle detector 34. The controller 36 adjusts rotational speed of themotor to keep the angle detected by the angle detector 34 within apredetermined range. The tension of the fiber bundle 8 supplied from thebobbin 11 is thereby kept constant. The control of the tension assiststhe resin impregnation device 3 in stably opening the fiber bundle 8 inexplained below. The desirable tension applied to the fiber bundle 8 is,for example, 300 g. The desirable traveling speed of the fiber bundle 8is, for example, 3 m/minute.

Means for keeping constant the tension of the fiber bundle 8 fed outfrom the bobbin 11 is not limited to the above tension adjustingmechanism 31. For example, the tension of the fiber bundle 8 can also bekept constant by a device including means for calculating a diameter ofthe fiber bundle 8 wound on the bobbin 11 through the use of thetraveling speed of the fiber bundle 8 and the number of revolutions ofthe bobbin 11 and means including a powder brake or the like to adjustthe brake torque of the bobbin 11.

<Fiber Preheating Machine>

The fiber bundle 8 supplied from the supply machine 1 is fed to thepreheating machine 2. The preheating machine 2 heats the fiber bundle 8to, for example, approximately 100° C. (a preheating step). This causesconvergence agent adhering to the fiber bundle 8 to be softened,facilitating opening of the fiber bundle 8 and impregnation of the fiberbundle 8 with thermoplastic resin in the next step. As the preheatingmachine 2, a known one can be used. The convergence agent is used forbringing a plurality of fibers into convergence to make them easy tohandle.

<Resin Impregnation Device and Nozzle>

The fiber bundle 8 having left the preheating machine 2 is fed to theresin impregnation device 3 via the guide roller 15. The resinimpregnation device 3 opens the fiber bundle 8 and impregnates the fiberbundle 8 with molten thermoplastic resin. In the resin impregnationdevice 3, the fiber bundle 8 is opened and the fiber bundle 8 isimpregnated with the molten thermoplastic resin (a resin impregnationstep).

The resin impregnation device 3 includes a container 3 a, an extrudingmachine 17, and a plurality of impregnation rollers 16. The container 3a has a cylindrical shape long in the conveyance direction of the fiberbundle 8 and stores the molten thermoplastic resin. The temperature ofthe molten thermoplastic resin is, for example, 230° C. The extrudingmachine 17 is connected to the container 3 a and supplies the moltenthermoplastic resin into the container 3 a.

The thermoplastic resin used in this embodiment is polypropylene, but itis not limited thereto. As the thermoplastic resin, there can be used,for example, acrylonitrile-butadien-styrene copolymer (ABS), polyamide(nylon 6, nylon 66, etc.), polyacetal, polycarbonate, high densitypolyethylene, low density polyethylene, straight-chain low densitypolyethylene, polyethylene terephthalate, polybutylene terephthalate,polyetherimide, polystyrene, polyethersulfone, polyphenylene sulfide,polyether ketone, and polyether ether ketone.

The plurality of impregnation rollers 16 are disposed at a predeterminedinterval along the conveyance direction of the fiber bundle 8 in thecontainer 3 a. Each of the impregnation rollers 16, which has a circularcross section, is disposed rotatably around the center axis thereofwhile making into contact with the fiber bundle 8 to thereby convey thefiber bundle 8 downstream. The impregnation rollers 16 can be replacedwith a guide bar, which has a circular cross section and is disposed soas to be prevented from rotation around the center axis thereof.

The fiber bundle 8 passes through the container 3 a in zigzag whilecoming into contact with each of the plurality of impregnation rollers16 in the container 3 a that store the molten thermoplastic resin asexplained above. In other words, the fiber bundle 8 passes through thecontainer 3 a while the contact of the impregnation rollers 16 with thelower surface of the fiber bundle 8 and the contact of the impregnationrollers 16 with the upper surface of the fiber bundle 8 are alternatelymade. The impregnation rollers 16 open the fiber bundle 8 through theabove contacts and, furthermore, the fiber bundle 8 is impregnated withthe molten thermoplastic resin.

The opening of the fiber bundle 8 is a processing of arraying theplurality of fibers which constitutes the fiber bundle 8 to spread themin a width direction orthogonal to the longitudinal direction of thefiber bundle 8 (the conveyance direction) to flatten the fiber bundle 8.The progress of the opening, therefore, involves increase in the widthof the fiber bundle 8 and decrease in the thickness of the fiber bundle8.

The number of the impregnation rollers 16 is adjusted according to thecondition of the opening of the fiber bundle 8 and of the impregnationof the fiber bundle 8 with the thermoplastic resin. Excessive number ofimpregnation rollers 16 open the fiber bundle 8 excessively to make thefiber density at each of the widthwise opposite ends of the fiber bundle8 be high. In addition, excessive number of impregnation rollers 16cause the tension of the fiber bundle 8 to be excessive great, whichmakes fiber cut easily occur. Conversely, insufficient number ofimpregnation rollers 16 fails to open the fiber bundle 8 sufficiently,thus making the fiber density in the widthwise center of the fiberbundle 8 be high and/or making the impregnation of the fiber bundle 8with the thermoplastic resin be insufficient.

The nozzle 18 is provided in the outlet portion of the container 3 a toshape the fiber bundle 8 discharged from the container 3 a. The nozzle18 encloses an opening of a rectangular slit, through which the fiberbundle 8 that has undergone the resin impregnation step passes (athrough-nozzle passing step). The fiber bundle 8 having passed throughthe nozzle 18 is spread into a tape shape having reduced thickness. Insummary, the nozzle 18 allows the fiber bundle 8 impregnated with thethermoplastic resin to pass through the nozzle while forming the fiberbundle 8 into the tape shape. In the following explanation, the fiberbundle 8 having passed through the nozzle 18 to be formed into the tapeshape may be referred to as a tape 9. The suitable temperature of thenozzle 18 is, for example, 230° C.

As shown in FIG. 3A and FIG. 3B, the nozzle 18 includes a first nozzlemember 18 a, a second nozzle member 18b, a pair of right and left shimplates (first shim plates) 41, a pair of right and left guide plates 42,and a pair of right and left shim plates (second shim plates) 43different from the pair of shim plates 41.

The first nozzle member 18 a and the second nozzle member 18 b accordingto this embodiment are arranged vertically so as to be verticallyopposed to each other. The pair of shim plates 41 and the pair of shimplates 43 can be selectively sandwiched between the first nozzle member18 a and the second nozzle member 18 b in respective positions at thewidthwise opposite (in the right-left direction) ends of the nozzle 18,thereby allowing a rectangular slit s to be defined between the firstnozzle member 18 a and the second nozzle member 18b. The gap dimensionof the slit s is, thus, allowed to be selected between a normaldimension L1 corresponding to the first thickness dimension of each ofthe pair of shim plates 41 and a production-start dimension L0 (>L1)corresponding to the second thickness dimension of each of the pair ofshim plates 43. Each of the pair of shim plates 41 and the pair of shimplates 43 is positioned to avoid contact with the fiber bundle 8 passingthrough the nozzle 18. The interval between the shim plates 41 and theinterval between the shim plates 43 are, therefore, larger than thewidth of a fiber-reinforced thermoplastic resin tape to be produced.

The pair of guide plates 42 is disposed so as to cover the right andleft end portions of the opening at the distal end of the nozzle 18 andattached to the first and second nozzle members 18 a and 18 b withscrews or the like. The pair of guide plates 42 is disposed at aninterval Wg, which has a dimension equal to the width of thefiber-reinforced thermoplastic resin tape to be produced, that is, whichdetermines the width. The width of the tape 9 having passed through theopening of the nozzle 18 is, thus, adjusted to the width of thefiber-reinforced thermoplastic resin tape to be produced. The intervalWg of the pair of guide plates 42, that is, the width that thefiber-reinforced thermoplastic resin tape to be produced should have,is, for example, 15 mm.

The gap dimension of the slit s defined in the nozzle 18 to allow thefiber bundle 8 to pass through the slit s is allowed to be changedthrough replacement of shim plates sandwiched between the first andsecond nozzle members 18 a and 18 b. FIG. 4 is a view of the nozzle 18at the start of production viewed from a direction of an arrow A1 inFIG. 1. FIG. 3B is a view of the nozzle 18 from a stage when apredetermined condition is satisfied after the production start viewedfrom the direction of the arrow A1. At the start of production of thefiber-reinforced thermoplastic resin tape, used is the pair of shimplates 43 shown in FIG. 4 and having the second thickness dimensionlarger than the first thickness dimension of the shim plates 41 shown inFIG. 3B, namely, the second shim plates. The second thickness dimensionof the shim plates 43 is larger than the thickness dimension of thefiber-reinforced thermoplastic resin tape to be produced, namely, atarget thickness dimension. Thus, at the start of production of thefiber-reinforced thermoplastic resin tape, as illustrated in FIG. 4, thegap dimension of the slit s is set to the production-start dimension L0(>L1) larger than the dimension L1 equivalent to the target thickness.Then, when the predetermined condition is satisfied after the productionstart, the shim plates 43 are replaced with the shim plates 41, therebychanging the gap dimension of the slit s from the production-startdimension L0 into the normal dimension L1 illustrated in FIG. 3B, i.e.,the dimension equivalent to the target thickness dimension. The firstand second nozzle members 18 a and 18 b and the shim plates 41 and 43,thus, constitute a dimension selection mechanism allowing the gapdimension of the slit s to be selected between the normal dimension L1and the production-start dimension L0 larger than the normal dimensionL1.

The “predetermined condition” is, for example, “predetermined time haselapsed after the production start”. Accordingly, “when thepredetermined condition is satisfied” can be rephrased as, for example,“if the predetermined time has elapsed”. The structure for making thegap dimension of the slit s of the nozzle changeable is not limited toone in the embodiment.

At the stage of passing the fiber bundle 8 through the container 3 a ofthe resin impregnation device 3, that is, at the stage before theproduction start, the fiber bundle 8 has not yet been openedsufficiently. If the fiber bundle 8 was pulled through the thin slit inthis state, the fibers and the nozzle 18 would be brought into strongcontact with each other in the slit portion to allow fiber cut to easilyoccur. Continuing the operation while leaving the fiber cut might causethe fiber having cut to clog the nozzle 18 to thereby cause all thefibers (the tape) to be cut. In order to prevent this, the change of thegap dimension of the slit s is performed.

“the start of production” means the time when the pulling machine 6begins pulling the fiber bundle 8. The normal dimension L1 is adimension corresponding to the thickness dimension that the (desired)fiber-reinforced thermoplastic resin tape to be produced should have,namely, the target thickness dimension.

The “predetermined condition” may be that, for example, the fiber bundle8 is opened up enough to have the width of the (desired)fiber-reinforced thermoplastic resin tape to be produced in a positionbefore the fiber bundle 8 reaches the slit s portion of the nozzle 18(e.g., in the container 3 a of the resin impregnation device 3). Thenumber of fibers (e.g., 12,000) constituting the fiber bundle 8 to bepassed through the slit s is determined on the basis of the width andthe thickness of the (desired) fiber-reinforced thermoplastic resin tapeto be produced, the type of material of fiber, and the type ofthermoplastic resin. This enables the fiber bundle 8 impregnated withthe thermoplastic resin when the fiber bundle 8 is opened up to have thewidth of the (desired) fiber-reinforced thermoplastic resin tape to beproduced to have a thickness substantially equal to the thickness of the(desired) fiber-reinforced thermoplastic resin tape to be produced.

The “predetermined condition”, alternatively, may be one based on thepulling speed of the tape 9 by the pulling machine 6. The pulling speed,that is, the production speed of the fiber-reinforced thermoplasticresin tape, is set to be a speed lower than normal pulling speed (speedfor production), at the start of production (at the start of operationof the apparatus) in order to prevent the tape 9 from being cut. Thepulling speed of the tape 9 is increased, after a certain degree of timeelapses, to predetermined pulling speed. On the premise that the pullingspeed of the tape 9 is thus increased with the elapse of time, the“predetermined condition” may be that the pulling speed of the tape 9reaches the predetermined pulling speed.

Alternatively, the “predetermined condition” may be that the fiberbundle 8 is opened enough to obtain the width that the (desired)fiber-reinforced thermoplastic resin tape to be produced should have,that is, obtain the target width, and that the pulling speed of the tape9 have reached the predetermined pulling speed.

Note that “the predetermined time elapses” may be that the time which isoptionally set for no particular reason has elapsed.

As shown in FIG. 1, FIG. 5, and FIG. 6, the impregnation roller 16closest to the nozzle 18 among the plurality of impregnation rollers 16is a grooved roller 19, which is formed with a groove 19 a shown in FIG.5. The grooved roller 19 according to this embodiment is single, but itis also possible to provide two or more grooved rollers on the sideclose to the nozzle 18. Besides, it is also possible to replace theimpregnation roller 16 with a guide bar which is also formed with agroove.

As shown in FIG. 5, the groove 19 a is formed in the axial center partof the grooved roller 19, having width We equivalent to the width of thefiber-reinforced thermoplastic resin tape to be produced, namely, thetarget width. The grooved roller 19 allows the fiber bundle 8 to passthrough the portion having the groove 19 a to thereby prevent the widthof the opened fiber bundle 8 from exceeding the width of thefiber-reinforced thermoplastic resin tape to be produced (i.e., thetarget width). The width We of the groove 19 a is equal to the dimensionof the interval Wg between the pair of guide plates 42 shown in FIG. 3B.

In this embodiment, in order to facilitate the change of the width ofthe fiber-reinforced thermoplastic resin tape to be produced, each ofthe impregnation rollers 16 upstream of the grooved roller 19 is formedof a flat roller having a cylindrical outer circumferential surface withno grooves. Alternatively, every impregnation roller 16 may be a groovedroller.

As shown in FIG. 6, respective widthwise centers of the plurality ofimpregnation rollers 16 including the grooved roller 19 and thewidthwise center of the nozzle 18 are aligned in a single straight linein plan view. This enables the fiber bundle 8 to run along the straightline, thereby suppressing unevenness in the density of the fibers in thefiber-reinforced thermoplastic resin tape to be produced.

<Cooling Roller Section>

As shown in FIG. 1, the tape 9 having passed through the nozzle 18 isfed to the roller cooling section 4. The roller cooling section 4includes a cooling roller 20 and a cooling roller 21 disposed in thisorder from the upstream side to the downstream side in the conveyancedirection of the tape 9. The cooling rollers 20 and 21 are kept at aconstant temperature (e.g., approximately 20° C.) through cooling watersupplied from a rotary joint (not shown in the figure). The coolingrollers 20 and 21 cool the tape 9 while feeding the tape 9 to thedownstream side (a cooling step).

The temperature of the tape 9 having passed through the nozzle 18 isequal to or higher than the melting point of the thermoplastic resin.Hence, the thermoplastic resin with which the tape 9 is impregnated isnot solidified immediately after having passed through the nozzle 18,which tends to cause widthwise evenness in the density in the runningfibers. The cooling roller 20 quickly cools the tape 9 immediately afterhaving passed through the nozzle 18. Specifically, the cooling roller 20cools the front side surface, namely, the upper surface in the figure,of the tape 9. Subsequently, the cooling roller 21 cools the back sidesurface (namely, the lower surface in the figure) of the tape 9. Throughthe cooling, the thermoplastic resin included in the tape 9 issolidified before the widthwise evenness in the density in the fibers ofthe tape 9 occurs.

<Cooling Section>

The tape 9 cooled by the roller cooling section 4 is fed to the coolingsection 5 shown in FIG. 1. The cooling section 5 cools the tape 9 withwater. The cooling section 5 is, for example, a water cooling pool. Thecooling section 5 may be one configured to cool the tape 9 with air. Ifthe cooling by the roller cooling section 4 is sufficient, it allows thecooling section 5 to be omitted.

<Take-Up Machine and the Winding-Up Machine>

The tape 9 cooled by the cooling section 5 is fed to the pulling machine6. The pulling machine 6 pulls and takes up the cooled tape 9. Thewinding-up machine 7 winds up the tape 9 pulled by the pulling machine6.

(Verification Experiment)

Performed was a verification experiment on the above-mentioned effect,that is, the fiber cut prevention effect achieved by setting the gapdimension of the slit s to be larger than the normal dimension at thestart of production of the fiber-reinforced thermoplastic resin tape andchanging the gap dimension of the slit s, when the predetermined timehad elapsed after the production start, into the normal dimension,through the use of an apparatus equivalent to the production apparatusshown in FIG. 1. Specifically, the verification experiment was carriedout with respect to the following example and comparative example.

In each of the example and the comparative example, as each of thefibers constituting the fiber bundle 8 was used a carbon fiber havingthe number of filaments of 12,000, fineness of 800 g/1,000 m, anddensity of 1.76. Polypropylene resin was used as the thermoplasticresin. The usual gap dimension (the normal dimension) of the slit s was0.06 mm.

In the example, the pair of thick shim plates 43 shown in FIG. 4 wasused at the start of production to set the gap dimension of the slit swas set to 0.15 mm, which was the production-start dimension. At a pointin time when the predetermined time had elapsed after the productionstart, the conveyance of the fiber bundle 8 was temporarily stopped,while the pair of shim plates 43 was replaced with the pair of shimplates 41 thinner than the pair of shim plates 43 to change the gapdimension of the slit s into 0.06 mm, which was the normal dimension,and then the production was resumed. This example was repeated fivetimes in total, in every time of which no fiber cut had occurred.

In the comparative example, operation was continued from the productionstart while the gap dimension of the slit s was kept at 0.06 mm. Thiscomparative example was also performed five times in total, in fourtimes of which fiber cut had occurred. This result indicates that makingthe gap dimension of the slit s be larger than the normal dimension atthe start of production makes it possible to markedly reduce frequencyof the fiber cut.

(Modification of the Nozzle)

FIG. 7A and FIG. 7B indicates a nozzle 22 according to a modification.The nozzle 22 includes a first nozzle member 22 a and a second nozzlemember 22 b which are opposed to each other. The first nozzle member 22a is formed with a groove 22 d, which forms the slit s having a widthdimension W and a gap dimension T equivalent to the normal gapdimension. At the start of production of the fiber-reinforcedthermoplastic resin tape, a pair of not-graphically-shown shim plates issandwiched between the first nozzle member 22 a and the second nozzlemember 22 b in respective positions on widthwise opposite outer sides ofthe groove 22 d to thereby increase the gap dimension of the slit sbeyond the normal dimension. At a stage when the predetermined conditionis satisfied thereafter, the shim plates are removed to reduce the gapdimension to the normal dimension. The operation of the apparatus isresumed in this state to thereby produce the fiber-reinforcedthermoplastic resin tape having thickness corresponding to the normaldimension.

As explained above, provided is a process and an apparatus for producinga fiber-reinforced thermoplastic resin tape, the process and theapparatus being capable of suppressing occurrence of fiber cut at thestart of production of the fiber-reinforced thermoplastic resin tape.

Provided is a process for producing a fiber-reinforced thermoplasticresin tape, the process including: a resin impregnation step of openinga fiber bundle and impregnating the opened fiber bundle with moltenthermoplastic resin; and a through-nozzle passing step of passing thefiber bundle having undergone the resin impregnation step through a slitformed in a nozzle to form the resin bundle into a tape shape. Thethrough-nozzle passing step includes passing the fiber bundle, at thestart of production, through the slit in a state where the slit has agap dimension larger than a normal dimension corresponding to a targetthickness dimension of the fiber-reinforced thermoplastic resin tape andchanging the gap dimension of the slit, at a point in time when apredetermined condition is satisfied after the start of production, intothe normal dimension and then passing the fiber bundle through the slit.

According to this process, setting the gap dimension of the slit largerthan the normal dimension equivalent to the target thickness dimensionof the tape allows the fiber and the nozzle to be restrained from strongcontact with each other in the slit portion to cut the fiber, at thestart of production of the fiber-reinforced thermoplastic resin tape,even if the opening of the fiber bundle is insufficient, thus preventingthat the fiber having cut clogs the nozzle to cause all fibers (i.e.,the tape) to be cut. At a stage when the predetermined condition issatisfied after the production start, for example, after a predeterminedtime elapses during which the opening of the fiber bundle progresses,fiber cut is not likely to occur in spite that the gap dimension of theslit is changed to the normal dimension at the point.

The “predetermined condition” is desirably that, for example, the fiberbundle is opened enough to allow the width of the fiber bundle to reacha target width which is a width of a fiber-reinforced thermoplasticresin tape to be produced.

At the stage when the condition is satisfied, where the fiber bundle issufficiently opened, the fiber and the nozzle can be prevented fromstrong contact with each other in the slit portion to cause the fiber tobe cut, in spite that the gap of the slit is changed to the normaldimension at the point in time when the condition is satisfied.

Alternatively, in the case where the through-nozzle passing stepincludes increasing production speed which is speed at which the fiberbundle passes through the slit, with the elapse of time from theproduction start, the predetermined condition may be that the productionspeed of the fiber-reinforced thermoplastic resin tape has reachedpredetermined speed. For example, it is also permissible to change thegap dimension of the slit into a predetermined dimension when pullingspeed of the tape reaches predetermined pulling speed.

According to this process, the production speed is increased from lowspeed, which restrains the fiber and the nozzle from strong contact witheach other in the slit portion at the start of production. In otherwords, setting the production speed to lower speed than thepredetermined (normal) production speed and setting the gap dimension ofthe slit larger than the predetermined dimension at the start ofproduction and changing the gap dimension of the slit, at a point intime when the production speed increases to the predetermined speed, tothe normal dimension makes it possible to more surely suppress fiber cutat the start of production.

Also provided is an apparatus for producing a fiber-reinforcedthermoplastic resin tape, the apparatus including: a resin impregnationdevice that opens a fiber bundle and impregnates the opened fiber bundlewith molten thermoplastic resin; and a nozzle provided in an outletsection of a container of the resin impregnation device and defining aslit allowing the fiber bundle impregnated with the thermoplastic resinto pass through the slit, the nozzle bringing the fiber bundle passingthrough the slit into a tape shape. The nozzle includes a dimensionselection mechanism allowing a gap dimension of the slit defined by thenozzle to be selected between a normal dimension equivalent to a targetthickness dimension of the fiber-reinforced thermoplastic resin tape anda production-start dimension larger than the normal dimension.

This apparatus, in which the production-start dimension larger than thenormal dimension at the start of production can be selected as the gapdimension of the slit and the gap dimension can be changed into thenormal dimension at a point in time when a predetermined condition issatisfied, after the production start, makes it possible to produce asatisfactory fiber-reinforced thermoplastic resin tape while preventingfiber cut from occurring at the start of production.

For example, the nozzle desirably includes a first nozzle member and asecond nozzle member disposed to be opposed to each other across theslit, a pair of first shim plates having respective first thicknessdimensions corresponding to the normal dimension and configured to besandwiched between the first nozzle member and the second nozzle memberat an interval widthwise of the slit between the first shim plates tothereby determine the gap dimension of the slit to a dimensioncorresponding to the first thickness dimension, and a pair of secondshim plates having respective second thickness dimensions larger thanthe first thickness dimension and equivalent to the production-startdimension and configured to be sandwiched between the first nozzlemember and the second nozzle member at an interval widthwise of the slitbetween the second sim plates to thereby determine the gap dimension ofthe slit to a dimension corresponding to the second thickness dimension.In this nozzle, sandwiching the second shim plates having respectivesecond thickness dimensions between the first nozzle member and thesecond nozzle member at the start of production allows the gap dimensionof the slit to be the production-start dimension to thereby preventfiber cut, and replacing thereafter the second shim plates with thefirst shim plates having the first thickness dimension to change the gapdimension of the slit into the normal dimension allows afiber-reinforced thermoplastic resin tape having the target thicknessdimension to be produced.

1. A process for producing a fiber-reinforced thermoplastic resin tape,the process comprising: a resin impregnation step of opening a fiberbundle and impregnating the opened fiber bundle with moltenthermoplastic resin; and a through-nozzle passing step of passing thefiber bundle having undergone the resin impregnation step through a slitformed in a nozzle to form the resin bundle into a tape shape, whereinthe through-nozzle passing step includes passing the fiber bundle, atthe start of production, through the slit in a state where the slit hasa gap dimension larger than a normal dimension corresponding to a targetthickness dimension of the fiber-reinforced thermoplastic resin tape andchanging the gap dimension of the slit, at a point in time when apredetermined condition is satisfied after the start of production, intothe normal dimension and then passing the fiber bundle through the slit.2. The process for producing a fiber-reinforced thermoplastic resin tapeaccording to claim 1, wherein the predetermined condition is thatpredetermined time elapses after the production start.
 3. The processfor producing a fiber-reinforced thermoplastic resin tape according toclaim 1, wherein the predetermined condition is that the fiber bundle isopened enough to allow a width of the fiber bundle to reach a targetwidth which is a width of the fiber-reinforced thermoplastic resin tapeto be produced.
 4. The process for producing a fiber-reinforcedthermoplastic resin tape according to claim 1, wherein thethrough-nozzle passing step includes increasing production speed, whichis speed at which the fiber bundle passes through the slit, with theelapse of time from the production start and wherein the predeterminedcondition is that the production speed reaches predetermined speed. 5.An apparatus for producing a fiber-reinforced thermoplastic resin tape,the apparatus comprising: a resin impregnation device that opens a fiberbundle and impregnates the opened fiber bundle with molten thermoplasticresin; and a nozzle provided in an outlet section of a container of theresin impregnation device and defining a slit allowing the fiber bundleimpregnated with the thermoplastic resin to pass through the slit, thenozzle bringing the fiber bundle passing through the slit into a tapeshape, wherein the nozzle includes a dimension selection mechanismallowing a gap dimension of the slit defined by the nozzle to beselected between a normal dimension equivalent to a target thicknessdimension of the fiber-reinforced thermoplastic resin tape and aproduction-start dimension larger than the normal dimension.
 6. Theapparatus for producing a fiber-reinforced thermoplastic resin tapeaccording to claim 5, wherein the nozzle includes a first nozzle memberand a second nozzle member disposed to be opposed to each other acrossthe slit, a pair of first shim plates having respective first thicknessdimensions corresponding to the normal dimension and configured to besandwiched between the first nozzle member and the second nozzle memberat an interval between the first sim plates widthwise of the slit tothereby determine the gap dimension of the slit to a dimensioncorresponding to the first thickness dimension, and a pair of secondshim plates having respective second thickness dimensions larger thanthe first thickness dimension and equivalent to the production-startdimension and configured to be sandwiched between the first nozzlemember and the second nozzle member at an interval between the secondsim plates widthwise of the slit to thereby determine the gap dimensionof the slit to a dimension corresponding to the second thicknessdimension.